Input: kbtab - sanity check for endpoint type

The driver should check whether the endpoint it uses has the correct
type.

Reported-by:  <syzbot+c7df50363aaff50aa363@syzkaller.appspotmail.com>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>